Transfer RNAs (tRNAs) are used as primers for reverse transcription during retroviral infection and may incorporate into the retroviral genome by illegitimate recombination. I am studying the tRNA gene cluster of the T-even bacteriophages as a model to investigate how they were incorporated into the viral genome. The tRNA genes vary widely among the T-even bacteriophages and have some features resembling reverse-transcribed mobile genetic elements. Additionally, each T-even phage expresses a unique set of tRNAs. The following questions will be explored. Are the tRNA genes mobile elements? Do they transpose via RNA intermediates? Is there sequence specificity at sites of loss or acquisition of tRNA genes? Is there illegitimate transfer of tRNA genes among the T-even bacteriophages or between them and other species? These questions will be approached by sequencing the tRNA gene clusters of phages T2, T4, and T6 to determine whether the tRNA genes are processed versions of tRNAs and to identify sites of loss or acquisition of tRNA genes. Genetic methods will be used to ask if these tRNA genes can transpose.